Many types of mechanisms for adjusting the tilt angle of work surfaces are known. However, the mechanisms suffer from a number of deficiencies.
Most tilt mechanisms are designed in the contemplation of surfaces which pivot at or near the front (i.e., the user's side) of the surface. As such, the mechanisms are designed with the idea of resisting downward pressure (i.e., force applied by objects which are resting on the surface). A work surface which has a pivot point located more toward the middle of the surface would be beneficial, since this would tend to balance the weight of the surface and any object carried thereon, so that adjustment of the surface could be carried out with less effort and greater control. In addition, when the pivot point is positioned near the middle of the surface, the front of the surface moves down as the rear of the surface moves up, thus permitting the surface to better accommodate the user in a number of different postures. However, the pivoting of the surface at a point towards the middle of the surface requires that the adjustment mechanism resist upward force as well as downward force, since a user will put downward pressure on the front of the surface, for example, when moving to a standing position or pushing away from the work surface. This downward pressure on the front of the surface results in upward pressure at the rear of the surface. Therefore, it would be desirable to have an adjustment mechanism which is capable of withstanding both upward and downward force.
In addition, many mechanisms are slow and cumbersome to operate. They often require the user to use both hands for operation and/or require the user to stand up to perform the adjustment operation.
Another benefit of a tilted work surface is the potential increase in available knee space under the surface made available as the surface is tilted. This is especially true if the user is using a foot rest. Unfortunately, many known mechanisms disadvantageously occupy a significant amount of space under the work surface.
Also, some known mechanisms for adjusting the tilt of a work surface suffer from the possibility of collapse of the work surface when the tilting mechanism is disengaged. This creates undesired noise and vibration, and can damage objects resting on the surface or even cause injury to the user. Some mechanisms which attempt to alleviate this problem rely on numerous and delicate parts and adjustment for safe performance. The number and nature of the parts increase the likelihood of failure over the course of time, posing the threat of injury to the user and damage to equipment carried by the work surface. Such mechanisms are also expensive and difficult to manufacture, thereby limiting the applicability of the mechanisms.
Most office applications require a work surface to tilt within an angle between horizontal and 13.degree. from horizontal. At angles larger than this, objects placed on the surface will tend to slide off the surface. Many known tilting mechanisms are not adapted to perform well within this limited range.